The Sharps are proof tested to 35,000 PSI. In the 45-70 for long range you are not using the modern light bullets. The lead 550 grs. Lyman Postell, 45-70 will deliver a heavy recoil from a 13 lbs. rifle. The 45-110 delivers the power of the 458. Lott. These are not mild sporting rifles.
The 45-70-550 . loaded with the paper patch can generate some serious power out to 1,000 yards.
Many shooters today use the puff "Cowboy loads" the Buffalo Hunters were not playing it was for real.